Metabolic cardiovascular syndrome and risk of dementia in Japanese-American elderly men. The Honolulu-Asia aging study.

Cardiovascular risk factors often cluster into a metabolic syndrome that may increase the risk of dementia. The objective of the present study was to assess the long-term association between clustered metabolic cardiovascular risk factors measured at middle age and the risk of dementia in old age. This prospective cohort study of cardiovascular disease was started in 1965 and was extended to a study of dementia in 1991. The subjects were Japanese-American men with an average age of 52.7+/-4.7 (mean+/-SD) years at baseline. Dementia was diagnosed in 215 men, according to international criteria, and was based on a clinical examination, neuropsychological testing, and an informant interview. The z scores were calculated for 7 risk factors (random postload glucose, diastolic and systolic blood pressures, body mass index, subscapular skinfold thickness, random triglycerides, and total cholesterol). The relative risk (RR [95% CI]) of dementia (subtypes) per 1 SD increase in the sum of the z scores was assessed after adjustment for age, education, occupation, alcohol consumption, cigarette smoking, and years of childhood lived in Japan. The z-score sum was higher in demented subjects than in nondemented subjects, indicating a higher risk factor burden (0.74 versus -0.06, respectively; P=0. 008). Per SD increase in the z-score sum, the risk of dementia was increased by 5% (RR 1.05, 95% CI 1.02 to 1.09). The z-score sum was specifically associated with vascular dementia (RR 1.11, 95% CI 1.05 to 1.18) but not with Alzheimer's disease (RR 1.00, 95% CI 0.94 to 1.05). Clustering of metabolic cardiovascular risk factors increases the risk of dementia (mainly, dementia of vascular origin).